Synthesis and Characterization of Electroless Ni-P/Ni-Mo-P Duplex Coating with Different Thickness Combinations

doi:10.1007/s40195-017-0603-6

Abstract

Abstract:

In this work, a novel duplex Ni-P/Ni-Mo-P coating upon the aluminum (Al) substrate was synthesized via an electroless plating, i.e., the binary Ni-P coating as a transition layer and the ternary Ni-Mo-P coating on the top. It was found that the duplex coating was of a high hardness, large elastic modulus, low porosity and excellent corrosion resistance. In addition, experimental results revealed that for a total 20 μm coating thickness, the duplex coating with a 7 μm of the Ni-Mo-P coating exhibited the best corrosion resistance in 0.5 mol/L sulfuric acid solution, which was attributed to its compact structure and low porosity. This duplex Ni-P/Ni-Mo-P coating with a thin ternary Ni-Mo-P layer is expected to solve the problem of low deposition rate of ternary alloy coating and thereby may expand applications of Al and its alloys in the fields of machine manufacture and corrosion environment.

Key words: Electroless plating, Aluminum (Al), Porosity, Ni-P/Ni-Mo-P duplex coating, Corrosion resistance

Gong-Sheng Song, Shuo Sun, Zhong-Chi Wang, Cheng-Zhi Luo, Chun-Xu Pan. Synthesis and Characterization of Electroless Ni-P/Ni-Mo-P Duplex Coating with Different Thickness Combinations[J]. Acta Metallurgica Sinica (English Letters), 2017, 30(10): 1008-1016.

Figures/Tables 12

Table 1 Chemical compositions of commercial pure aluminum (Al) substrate (wt%)

Si	Fe	Cu	N	Al
0.15	0.015	0.015	0.005	Bal.

Table 2 Parameters for every process

Process	Solution composition	pH	Temperature (°C)	Time (min)
Cleaning	Anhydrous ethanol		25	1
Alkaline degreasing	20 wt% sodium hydroxide solution		40	0.3
Acid pickling	20 vol% nitric acid		25	3
Electroless Ni pre-plating	13 g/L nickel sulfate 30 g/L sodium hypophosphite 40 g/L sodium citrate 30 g/L ammonium chloride	9-10	50	5
Electroless binary Ni-P plating	27 g/L nickel sulfate 30 g/L sodium hypophosphite 20 g/L sodium acetate 1.2 g/L sodium citrate 31 mL/L lactic acid 3.7 mL/L propionic acid 5 mg/L copper sulfate 5 mg/L sodium thiosulfate	5	91 ± 1	60
Electroless ternary Ni-Mo-P plating	31 g/L nickel sulfate 31 g/L sodium hypophosphite 20 g/L sodium pyrophosphate 40 g/L ammonium sulfate 0.8 g/L sodium molybdate 10 ml/L triethanol amine 1 mg/L thiourea 0.05 g/L sodium dodecyl sulfate 1 g/L saccharin	9	70 ± 1	60

Fig. 1 SEM images of a Ni-P coating, b Ni-P/Ni-Mo-P duplex coating

Fig. 2 EDS analysis of a Ni-P coating, b Ni-P/Ni-Mo-P duplex coating

Fig. 3 EDS elemental mapping analysis of Ni-P/Ni-Mo-P duplex coating: a SEM image; b Ni element; c Mo element; d P element

Fig. 4 XRD patterns of Ni-P coating and Ni-P/Ni-Mo-P duplex coating with 7 μm of Ni-Mo-P coating

Fig. 5 XPS spectra of Ni-P/Ni-Mo-P duplex coating a-d (a full scope spectrum, b Ni 2p spectrum, c Mo 3d spectrum, d P 2p spectrum) and Ni-P coating e-f (e full scope spectrum, f Ni 2p spectrum, g P 2p spectrum)

Fig. 6 SEM morphologies of duplex Ni-P/Ni-Mo-P coating with different thicknesses of outer Ni-Mo-P coating: a 4 μm, b 7 μm, c 10 μm, d 13 μm, e 17 μm, f cross-section morphology of Ni-Mo-P coating of 7 μm (total thickness was 20 μm)

Fig. 7 Porosity of Ni-P coating and Ni-P/Ni-Mo-P duplex coatings a and potentiodynamic polarization curves of bare Al, Ni-P coating and Ni-P/Ni-Mo-P duplex coatings with different thicknesses of outer Ni-Mo-P coating in 0.5 mol/L H2SO4 solution (total thickness was 20 μm; Ecorr: corrosion potential; Icorr: corrosion current density) b

Table 3 Potentiodynamic polarization tests of bare Al, Ni-P coating and Ni-P/Ni-Mo-P duplex coatings with different thicknesses of Ni-Mo-P coating in 0.5 mol/L H2SO4 solution (Ecorr: corrosion potential, Icorr: corrosion density)

Thickness of Ni-Mo-P coating (μm)	E_corr (V)	I_corr (A/cm²)
Bare Al	-1.205	5.624 × 10^-4
0 (Ni-P coating)	-0.113	7.385 × 10^-6
4	-0.126	3.285 × 10^-6
7	-0.086	1.526 × 10^-6
10	-0.098	2.332 × 10^-6
13	-0.430	2.929 × 10^-6
17	-0.478	8.560 × 10^-5

Fig. 8 Load-displacement curves a and fitted results of hardness and elastic modulus b of bare Al, Ni-P coating and Ni-P/Ni-Mo-P duplex coatings

Fig. 9 Load-displacement curve showing jump point at interface between Ni-P coating and Ni-Mo-P coating of Ni-P/Ni-Mo-P duplex coating

References

[1]	Y.B. Unigovski, A. Grinberg, E. Gerafi, E.M. Gutman, Surf. Coat. Technol. 232, 695(2013)
[2]	W.S. Miller, L. Zhuang, J. Bottema, A.J. Wittebrood, P. De Smet, A. Haszler, A. Vieregge, Mater. Sci. Eng.,A 280, 37(2000)
[3]	W. Qin, J. Coat. Technol. Res. 8, 135(2010)
[4]	Y.S. Huang, Adv. Mater. Res. 189-193, 265(2011)
[5]	A.E. Fetohi, R.M.A. J. Ind. Eng. Chem. 30, 239(2015)
[6]	N. Nagata, T. Kanadani, K. Nakagawa, M. Fukuhara, K. Horikawa, K. Murakami, M. Hino, J. Jpn. Inst. Met. 79, 151(2015)
[7]	N. Nagata, T. Kanadani, K. Nakagawa, M. Fukuhara, K. Horikawa, K. Murakami, M. Hino, J. Jpn. Inst. Met. 79, 146(2015)
[8]	L.W. Ren, Z. Wang, M.M. Meng, H. Tian, H.J. Yang, J.W. Qiao, J. Non-Cryst. Solids 430, 115(2015)
[9]	A.E. Fetohi, R.M.A.Hameed, K.M. El-Khatib, E.R. Souaya,Int. J. Hydrogen Energy 37, 10807(2012)
[10]	M.L. Wang, Z.G. Yang, C. Zhang, D.L. Liu, Trans Nonferrous Met. Soc. 23, 3629(2013)
[11]	X. Shu, Y. Wang, X. Lu, C. Liu, W. Gao, Surf. Coat. Technol. 276, 195(2015)
[12]	E. Valova, S. Armyanov, G. Hristova, T. Vassilev, O. Steenhaut, J. Dille, A. Hubin, I. Vandendael, Surf. Coat. Technol. 304, 468(2016)
[13]	X.L. Wang, Y.X. Zheng, M.L. Jia, L.S. Yuan, C. Peng, W.H. Yang, Int. J. Hydrogen Energy 41, 8449(2016)
[14]	J. Li, D. Wang, H. Cai, A. Wang, J. Zhang, Surf. Coat. Technol. 279, 9(2015)
[15]	G. Lu, G. Zangari, J. Electrochem. Soc. 150, C777(2003)
[16]	Y.H. Chou, C.Y. Bai, M.D. Ger, C.L. Chao, S.J. Lee, C.Y. United Kingdom, 2007, pp. 21-24
[17]	A.E. Fetohi, R.M.A. J. Power Sources 240, 58(2013)
[18]	D.L. Liu, Z.G. Yang, C. Zhang, B 166, 67(2010)
[19]	R.C. Agarwala, V. Agarwala, Sadhana 28, 475(2003)
[20]	H. Liu, Y.Y. Lv, Z. Liu, H. Liu, G.E. Thompson, Tribol. Int. 103, 343(2016)
[21]	V.E. Selvi, P. Chatterji, S. Subramanian, J.N. Balaraju, Surf. Coat. Technol. 240, 103(2014)
[22]	C. Subramanian, K. Palaniradja, Int. J. Metall. Eng. 4, 25(2015)
[23]	Y. Wang, X. Shu, S. Wei, C. Liu, W. Gao, R.A. Shakoor, R. Kahraman, J. Alloys Compd. 630, 189(2015)
[24]	J. Sudagar, J. Lian, W. Sha, J. Alloys Compd. 571, 183(2013)
[25]	S. Sun, G.S. Song, Z. Ma, Surf. Technol. 45, 49(2016). (In Chinese)
[26]	L.M. Abrantes, A. Fundo, G. Jin, J. Mater. Chem. 11, 201(2001)
[27]	X.B. Xi, H. Miao, R.H. Zhang, J. Cheng, Surf. Coat. Technol. 297, 27(2016)
[28]	J.N. Balaraju, N. Raman, N.T. Manikandanath, Trans. Inst. Met. Finish. 92, 169(2013)
[29]	H.M. Lee, H. Chae, C.K. Kim, Korean J. Chem. Eng. 29, 1259(2012)
[30]	J.C. Hsu, K.L. Lin, Thin Solid Films 471, 186(2005)
[31]	M. Sribalaji, O.S. Mater. Chem. Phys. 177, 220(2016)
[32]	A.S. Hamada, P. Sahu, D.A. Porter, Appl. Surf. Sci. 356, 1(2015)
[33]	P. Wiecinski, J. Smolik, H. Garbacz, J. Bonarski, A. Mazurkiewicz, K.J. Kurzyd?owski, Surf. Coat. Technol. 309, 709(2017)